Excavating machine



Nov. 8, 1932. R ow 1,886,381

EXCAVATING MACHINE Filed Dec. 26. 1929 4 Sheets-Sheet 1 Z9 INVENTPRATTORNEY Nam-8, 1932. R. R. DOWNlE EXCAVATING MACHINE Filed Dec. 26,1929 4 Sheets-Sheet 2 &N

ATTO NEY INVENTOR RJfflmz/nze R. R. DOWNIE EXCAVATING MACHINE Filed Dec.26, 1929 4 Sheets-Sheet- M W 1 h O Z 9 7 0 w 7 0 w J Nov. 8, 1932.

Patented Nov. 8, 1932 ROBERT REX DOWNIE F BEAVER FALLS, PENNSYLVANIAEXCAVATING MACHINE Application filed December 26, 1929. Serial No.416,629.

This invention relates to improvements in excavating machines,especially those, excavating machines known as clamshells.

Among other objects, the invention aims to provide means for deliveringa heavy thrust to the clamshell bucket during the taking of the load, sothat excavating in hard earth and-even in rocky soil may be undertakenby a clamshell excavator.

Another object is to provide, in a machine of this character, means forpreventing the upward pull of the bucket closing line from diminishingthe engagement weight of the bucket.

A further object is the provision of a machine of this character havingbut two power members and no other channels of control for actuating andcontrolling the bucket and boom in all movements in the vertical planeof operation.

The invention has other objects which will appear from the followingdescription.

Referring to the accompanying drawings, forming a part of thisspecification and showing the simplest form of the invention now knownto me,

Fig. 1 is a side elevation of a machine embodying the invention, showingthe boom, and bucket and control means therefor, but

only a portion of the handling machine;

Fig. 2 is an enlarged plan View showing the manner in which a singlepower actuated line actuates two bucket-closing lines through relaydrums, the view being substantially on the line 2--2 of Fig.1;

Fig. 3 is an end elevation from the left end of Fig. 1 on an enlargedscale, the bucket, the handling machine and other distant parts beingomitted;

Fig. 4 is an enlarged elevation showing the outer end of the boom andthe parts carried thereby;

Fig. 5 is an enlarged sectional elevation of the details of constructionshown in F 4;

Fig. 6 is a large scale elevation of the bucket, the View being from thesame position as Fig. 1 except showing the bucket closed;

7 is a side elevation of the bucket of Fig. 6;

Fig. 8 is a section on the. line 88 of Fig. 4 but drawn to a stilllarger scale; and

Fig. 9 is a section on the line 99 of Fig. l, drawn on the same scale asFig. 8. 1

Referring particularly to the drawings, there is shown the digging endonly of a standard handling machine, whose construe tionforms no part ofthis invention and hence is not disclosed. In this instance, thehandling machine illustrated is a standard non-revolving excavator;however, the handling machine may be of the type shown in my pendingapplication, Serial N 0. 411,523, filed December 4:, 1929, or of thetype disclosed in my pending application, Serial No. 298,501 filedAugust 9, 1928, or any other revolving excavating machine: The essential parts of any such a machine are a traction base, a frame mounted onthe traction base, an engine carried by the frame, provision forhorizontal swinging, at least two drums driven by the engine, andsuitable control. means for starting, stopping and holding the rotarydrums, a line or cable being wrapped around each drum and passing out tothe boom and scoop.

Only two lines are employed to effect all excavating movements of thescoop and these two lines are under the constant control of the operatorwho operates the drums by means of two hand. levers. Side swinging ofthe boom, as for discharging of the spoil, is effected by a third drumcontrolled by a treadle, thus making it possible for the operator tomaintain his complete controlv of the position of the scoop during sideswing- I ing.

Herein, the handling machine of Fig. 1 includes a traction base 15,which is shown diagrammatically, a frame 16, a boom 17 pivoted to swingvertically, as at 18, and capable of swinging horizontally along withthe vertical mast 19 which turns aboutthe vertical axis of pivot pins20. A power actuated line 21 passes around the segmental grooved sheave22 to which the hoisting line is attached by means of a yoke, so thatrotation of the sheave is followed .by boom and mast.

In order to elevate and lower the boom, a hoisting line 23 is provided,said hoisting til line extending from the swing yoke 24 to and about asheave 25 fixed near the outer end of the boom, and thence to guidingsheaves on the mast and machine and to the engine-driven drum (notshown). A. sheave stand 26 fixed at the outer end of the boom elevatesthe sheave 25 a considerable distance above the boom so as to obviateinterference of the hoisting line 23 and other parts to be described.This sheave stand is so made as to be readilyremovable to permit theboom 17 to be used with other excavating devices, for example, a ditcherat-' tachment, as disclosed in my Patent No 1,511,114. :I

By means of the above described mechanism, the boom may be hoisted andlowered, being swingable through an angle of 136 or more in a. verticalplane and also being swingable through an angle 180 more or less in ahorizontal plane. If the boom is mounted on the machine of my'pending application, Serial No. 411,523, filed December 4, 1929, it will becapable or horizontal swinging in a total arc of 360.

Mounted upon the boom, in a manner to be described, is a. column chainconsisting of a series of link elements, and constructed and arranged totransmit longitudinally any pressure or thrust imposed upon it; in othewords, capable of withstanding compression forces without buckling or.yielding. The clamshell bucket is carried at the lower end of the columnchain and will be described hereinafter.

As is customary in clamshell buckets, the bucket is elevated by acontinuation of the. same power application by which the jaws areclosed. In this instance, there is a pair of bucket closing andelevating lines 27 (see Figs. 1, 2 and 3,) said lines passing aroundguiding sheaves 28 at the outer end of the boom and thence to respectiverelay drums 29, which are mounted on a common shaft with the drum 30, asshown at Fig. 2, the three drums being on the boom 17 near its outerend. A main bucket-controlling line 31 is wrapped around drum 30 andpasses around guiding sheaves to the previously mentioned engine-drivendrum by which the scoop or bucket is controlled.

By the described construction, when the line 31 is pulled in by theengine, the two lines 27 will close the bucket (it previously open) andthen hoist the bucket together with the column chain.

Referring to Figs. 1, 6 and 7 the clamshell bucket or scoop has two jaws32 which are pivot-ed as by a pivot pin 33 and whose digging edges arearmed with excavating teeth 34. The lines 27 are connected with thepivot pin 33 in a manner to be described, and the jaws are so mountedthat when the pivot pin is raised, the two jaws close. In order toeffect closing of the jaws without an accompanying elevation of t 1eclamshell, provision is made for transmitting pressure from the boomthrough the medium or the column chain to the jaws, so that the teeth ofsaid jaws are forced to bite into the earth or other material beingexcavated- To transmit such pressure to one of the jaws, a pair of arms35 are provided, each secured at its upper end to a head-piece 36 whichis attached to the lower end of the colui'nn chain, as will bedescribed. The lower end of each arm 35 is pivoted to the jaw. The otherjaw is connected by a pair of links 37 to the head-piece, each linkbeing pivoted to both the head-piece and the jaw. It will be obviousthat any pressure exerted upon the head-piece will be transmittedthrough the arms 35 and links 37 to the corresponding jaws of the scoopand will tend to force the teeth 34- downwardly when the jaws are wideopen, as in Fig. 1. Furthermore, it will be evident that as long as thispressure is maintained, the closing or the jaws by means of the lines 27will not effect any material elevation of the bucket.

In order to guide the bucket closing lines 27 to the sheaves 38, a yoke39 is provided, said yoke being pivoted to the head-piece 36 for angularmovement in the transverse vertical plane. The yoke 39 is pivoted as at0 and carries a pair of upper rollers or sheaves 1-1 and a pair of lowerrollers or sheaves 12, the two pairs of sheaves being at each end of theyoke and lying in planes at right angles to each other, as clearly shownin Fig. 7. Each line 27 passes between the two sets of rollers 11, anddown around the cone sponding sheave v33, the two sheaves being mountedon a common axle carried by a yoke 13, passing around the main pivot pinof the clamshell. The yoke i3 is so formed and arranged that the reachesof the cables 27 between the sheaves 38 and the sheaves 28 at the end 01the boom may normally lie straight, parallel with each other, andcentered in the transverse vertical center plane ofthe scoop, and thusmay be received upon sheaves 38 without side draft and without exertinga twisting force upon the scoop or upon the column chain which isattached to the scoop. The ends of lines 2'? are attached to theopposite ends of an equalizing bar 14, said equalizing bar beingpivoted, as at (Fig. 6) to the head-piece 36.

It will beclear that the lines 27 work in two parts, while closing theaws of the scoop, and thereafter while hoisting it work in single partwithout any movement of the sheaves 38. The sides of the grooves of thesheaves or rollers and 42 lit the lines 17 fairly closely, but in thegrooves of sheaves 38 allowance is made for a slight disalinemcnt of thesheaves, which occurs at certain intermediate points in the opening andclosing movements of the scoop.

' the pivot pins 47 Referring to Figs. 3, 4 and 8, the previouslymentioned column chain is shown as comprising, in this instance, twodouble link sprocket chains including links 46 and pivot pins 47. Thetwo sprocket chains are parallel and identical in all respects and theiropposed inner links are connected by \l-shaped yokes 48 operativelyintegral with said links, and having integral spacer blocks 49. Thespacer blocks 49 with the yokes 48 provide generally T-shaped spacingmembers which are normally separated a small fraction of an inch,

but which abut against each other as soon as any compression stressesare imposed upon the column chain. WVhcn this occurs, the column chainwill assume a very slightly bowed shape, as shown in Fig. 1; and when inthis condition, the column chain may transmit a very heavy thrust to theclamshell bucket.

It will be clear that the chain links 46, together .with their pivots4?, permit the column chain to support a load under tension, that is,the load arising from the attachment of the clamshell to the lower endof the column chain and from any excavated material which may be withinthe bucket. The spacer blocks 49 sustain a compression or column load,as for example, when the boom hoist line is slackened and the effectiveportion of the weight of the boom is supported by the column chain. SeeFig. 1.

As indicated in Fig. 7, the lowermost links of the column chain arepivotally connected to ears 5O projecting above the yoke 39. Thus thescoop has two horizontal axes of movement with reference to the columnchain, the one longitudinal and the other transverse; and movement mayoccur about either axis independently of movement about the other; thusthere is provision for universal movement of the scoop relative to thecolumn chain. The objects of this construction are, first, to permit thescoop to accommodate itself freely to the face of the work,

- and second, to avoid eccentric loading and possible binding of thechain, which binding might interfere with the column setting of thechain, as will be understood by referring to Fig. 1.

The column chain, in the illustrative embodiment, is carried by the boomin such a Way that the unused length thereof is stored upon the boom.vIt will be clear that the chain is flexible in one direction because ofand hence the chain may be, and preferably is, passed around a pair ofsprockets 51 suitably designed for engagement with the pivots 47, saidsprockets 51 being mounted on a shaft 52, which is carried by a bracket53 depending from the outer end of the boom and providing a housing forthe sprockets and for a brake drum 54 and associated parts, by means ofwhich the sprockets are secured against rotation, thereby to preventtravel of the chain on or 0H the boom (see Fig. 4). VVhile only onebrakev drum is shown in Fig. 3, if desired, two

be prevented. The brake lever 57 is guided by a curved guide 58 securedto the boom and has an adjustable connection with a link 59, which ispivotally connected thereto and also to an arm 60 connected with the hub61' of sheave 25. The arm 60 has a pivoted cap,

or hub connection 62, which by means of the spring 62, lightly grips thehub 61, the

pressure of said spring being adjustable, as-

indicated. As the cap 62 lightly grips the hub 61, arm 60 tends torotate with the sheave 25 when the boom hoist line is pulled in or letout. However, arm 60 is permitted to oscillate only through a small are,there being a pair of stops 63 projecting from the sheave stand 26 (Fig.8), to limit the movement of the arm to an arc of about 90.

From the foregoing, it will appear that when the boom hoisting line 23is pulled in by the power actuated drum to hoist the boom, the sheave 25will be rotated in a counterclockwise direction and will tend to movethe arm 60 in the same direction, but said arm will be stopped by therighthand stop 63 of Fig. 4. When the line 23 is slackened to permit theboom to descend, the sheave 25 will be rotated in a clockwise directionand the arm 60 will quickly move to the dotted line position of Fig. 4,where it will be stopped by the lefthand stop 63. In the dotted lineposition, the arm 60, in conjunction with the adjustable link 59,provides a toggle lock for the brake lever 57, so that the brake is setin this position of the parts. When the brake is set, the sprockets 51cannot rotate and the column chain can neither rise nor descend but mustset as a column when a compression load is imposed upon it.

As shown in Fig. 5, the adjustable link 59 is in two parts and is madeso as to be nonresilient under tension (as in releasing the brake 54),but yields to a certain compress sive force determined by the resistanceof a compression spring 64 carried by the link. Secured to one of theparts of link 59 is a sleeve 65 screw-threaded at one end, as shown, andhaving a longitudinal slot 66 receiving a pin 67, which is fixed to andprojects radially from the other part of the link 59. The compressionspring 64 is interposed between a shoulder piece 68 (fixed to the samepart of the link which carries the sprockets may 7 in its movement inthe reverse direction upon v gers supporting the rails so as pin 67) andone or more tension adjusting nuts 69 on the threaded end of sleeve 65.fhe compressive resilience of the link 59 permits the am 60 and the linkto have a toggle action at the brake-setting end of travel of the arm60, which serves to hold the arm 60 and the brake lever 57 againstcasual releasing movement. Furthermore, the resilience of link 59serves, to some extent, as an auto matictake-up for wear of the brakeband 55. It will also be clear that the operator, by controlling thehoist line 28 in the usual manner, 'may obtain perfect control overmovements, of the column chain, without the necessity for themanipulation of an additional lever or power element. 1

While the boom itself could be made of such length and of suchproportions as completely to enclose and receive the entire length ofthe column chain, in this instance I have shown an arrangement of partsnow preferred by me, whereby the column chain is stored on a rackmounted on the underside of the boom.

Referring to Figs. 4, 8 and 9, and first to Fig. 8, the boom 1'? hassecured thereto a plate 70, with angles 71 at the corners for supportingthe brackets 53. Secured to the brackets 58, and extending between them,is a cross piece 72 providing a support for pairs of U-shaped clips 73,to which are welded spaced rails 74. The space between the rails 74exceeds the diameter of the pivot pins 47 of the sprocket chains, andsaid pivot pins are slidable along the rails 7% with the links of thechains both inside and outside of the two rails between which the pivotpins pass.

1 1e rails 74 are spaced a sufficient distance below the boom 17 toprovide clearance for the yokes 48 and the spacer blocks 49, the rails74 extending practically the entire length of the boom, as shown in l,and may be curved, as at 75, near the pivoted end of the boom, so as topermit the column chain to move around the tracks and forwardly on asecond tier of the rack, when the chain is elevated. At intervals,hangers 76 are provided, as best shown in Fig. 9, said hanto be spacedapart from each other and yet rigidly secured upon the boom.

If desired, instead of the rails being curved at the point l5, a rolleror a pair of idler be provided to assist the chain the lower tier of therack. W hen the clamshell bucket is in its uppermost position, andpractically the entire length of the column chain is stored upon therack, provision is made for stopping the upward movement of the chain bystop pieces 7'? 6 and 7) which are fixed to the two sets of links nextto the lowermost links otthe chain. These stop pieces or blocks aresuitably shaped to contact atone side with the edges oi the rectedfinger 81 for contacting with the low-' ermost spacer block 49. Thusthecounterweight 7 9 tends to throw the column into the slightly bowedposition of Fig. l'as' soon' as the column chain is relieved of anypartof the weight of the bucket, as when the bucket encounters thematerial to be excavated.

The operation Assuming the machine to be in the position of 1, theclosing line 31 is wound in by power, thus pulling in lines 27 andclosing the jaws of tie clamshell so that the load is gathered by thejaws. During this operati 1, the efi'ective per vion ot the weight ofthe mini is allowed to bear upon the clamshell durin that-is, during thedownward and raking movements of the teeth. However, the hoisting linemaybe pulled in to elevate the boom slightly and to relieve the pressureon the column chan during the final stage of the bucket closingmovement. The sheave 25 is rotated sufiiciently by this preliminaryhoisting movement of cable 23 to swing the friction arm 60 out or" thebrake-applying position, so as to release the brake 54.

By the above method of operation, the inwinding or cable 31 and itsextensions 27 may be continued from the scoop closing stage into thescoop hoisting stage, without interruption. However, as an alternativemethod, the inwinding of the closing line 31 may be suspended'as soon asthe scoop is closed and the hoisting line 23 may then be wound insuficiently to revolve sheave 25 and thus release the brake and theinwinding of line 31 may then be resumed.

The possibility of unintentional continued winding of the closing line,after closing has been completed and before the brake has een released,is provided for by proper adjustment of the length of link 59 and thepressure of spring 62 (Fig. l). These are so adjusted that when the armis in its brakesetting position, the brake will be applied with littlemore than suliicient force to sup port that portion of boom weight whichmay be delivered upon the chain and to provide the necessary reaction tothe normal digging pull of cables 27. Thus, inthe event that the line 31is wound in after the scoop is closed, against the resistance of thesaid brake, the chain will be subjected only to little more than itsnormal load and the overload willthe period of greatest effectiveness,

cause the brake to slip until released. All of these parts are designedto be strong enough to withstand the full power of the lines, so that nobreakage of parts, but only waste of power, can result from operatingerrors.

As the scoop is orawn up by means of cables 27, the links of the columnchain are deflected by the guides 78 into the raclr. Hoisting by meansof cable 23 may be star ed at any convenient time. Elevation of the boomfrom the horizontal position of 1 (which is the preferred position fordigging because it is the position inwhic the boom. weight is mosteiiective), shortens the working radius or horizontal distance from thevertical center line of the load to the swinging axis of the machine;and if there are cross braces or bulk-heads in the trencl with which thescoop would interfere, if its working radius were shortened duringhoisting, then the boom hoisting is postponed until after the scoop has.risen clear of the obstructions. Then the scoop is held shut by cables27 and the boom and scoop are hoisted to a suitable height by cable 23and the boom is swung about to the point of discharge. At this time,thehub of sheave 25 slips relative to the friction arm 60, the armremaining against the right-hand stop, l. When the scoop has beenstopped for discharge, the boom is lowered sufficiently to revolvesheave 25, and arm 60 in a clockwise direction, so as to set the brake54-. Then the closing line 31 is slacked oil and the weight of the scoopand load are carried by the column chain, then under tension, and thescoop opens to discharge the load. The boom is. then swung back to andlowered over the work, with the open scoop supported by the columnchain, with the hub of sheave 25 slipping relative to the arm 60 duringthe boom lowering operation.

There are alternative methods of lowering the scoop to the floor of theexcavation. After the boom has been lowered to the approximate positiondesired for the loading operation, the boom may be raised suiiiciently 1artially to release the brake 5% so that the open scoop will descend,supported or checked by the column chain tension, and under the controlof the hoisting cable 23 through the medium of the sheave 25 and brake54, until the scoop strikes the material.

Instead of this operation, the closing line 31 may be drawn in, closingand taking the weight of the scoop, and the hoisting cable would then bedrawn in suiliciently fully to release the brake 54-, inci-c cntallyraising the boom slightly, and the scoop may then be lowered undercontrol of line 31. By this last method, when the scoop approaches to apoint within two or three eet of the floor of the excavation, the hoisno; line is released a little so as to setthe brake and transfer theweight of the scoop onto the chain, and the closing line is then freelyreleased to permit the scoop to open, just clearing the material.

The boom is nowlowered, permitting the scoop to rest upon the material,as in Fig. 1.

With continued lowering of the boom and relieving of; the tension on thecolumn chaln,

comes effective, and the counterweight lifts the lowermost spacer blockuntil it comesinto contact with the spacer block adjacent to and aboveit. Each spacer block in turn tends to come in contact'with the spacerblock above, and the final result is that the chain assumes slightlybowed shape, which is maintained by pressure of the boom weight, Whenthe chain isin the position of Fig. 1, the spacer blocks are carrying acompression load throughout the entire length of the chain from the endof the boom downwardly to the ucket, while the links proper carrycompression over certain portions of the length of thechain and carrytension in the remaining portion of the chain.

While it is preferred to employ a simple weighted arm for setting thechain, that is, for putting the chain in such position that it cannot becollapsed by'boom weight or its equivalent, alternative mechanisms,within the scope of the broader claims, may be used. F or instance,tension springs may be employed extending from each link to the nextalong a line intermediate between the pitch line of the chain proper andthe center line of the series of spacer blocks, the springs havingsufficient initial tension to pull the unrestrained chain into aslightly bowed position, as in Fig. 1, but yielding to permit the chainto pass over the sprockets at the end of the boom. g

As anothermeans for setting the chain, 1 may employ an arm pivotallyattached to the boom near the outer end thereof and depending from theboom and carrying an idler sprocket at its lower end, the idler sprocketpressing against the standing part of the chain so as to bow the chainin the proper direction to take a column load. The idler sprocket shouldbe yieldingly pressed against the chain, either by a spring or by aweight, so as to cause pressure to be exerted by the idler against thecolumn chain. The more fully described counterweighted arm is preferred,because of its simplicity and inexpensiveness and because thecounterweighted arm does not lessen the clearance height of the scoop.

From the above, it will be clear that the described machine providesmeans permitting the delivery of boom weight upon the scoop during thetaking of theload to increase the engagement force and thus to permitpenetrating and digging harder material with a givenweight of'scoophaving a given length of cutting edge than is possible with a scoop notmaintained or backed by external force. Thus, it is possible, with thepresent invention, to make a clamshell bucket dig materials of ahardness heretofore considered prohibiting the use of such buckets.

The described machine is also advantageous in that the upward tilting ofthe closing line does not lessen the ground-engagement weight of thescoop. The excavating machine of this invention also has a more rapidbucket closing action with a given closing force than is obtainable in aclamshell having only cable connection with the boom.

The usual working position of the boom will be horizontal, as in Fig. 1,and in this position the-maximum weight may be imposed upon the bucketduring diggin As the column chain descends, more and more of its weightis eliective for increasing the penetration of the teeth. When thecolumn chain is largely carried by the boom, the weight of the'boom willnecessarily be increased and this increased weight is, of course,effective, when the column chain is set, to cause the bucket to biteinto the material. However, as the boom is pivoted, only about one-halfof its total weight, including the weight of the carried chain, may beimposed upon the vertical length of the column chain. As the columnchain moves ofi' the boom, the compressioncolumn increases in length andhence inweight, and thus becomes increasingly effective to force thebucket down through very hardmaterial.

The machine is so constructed as to make unnecessary the use of one ormore poles or other hold-down means attached to the scoop and madevertically slidable at the end of the boom for scoop hoisting. Suchhold-down devices are very unwieldy when side-swung in hoisted position,and in city work are certain to interfere with trees, overhead wires,and the like.

Obviously, the present invention is not restricted to the particularembodiment thereof herein shown and described. Moreover, it is notindispensable that all the features of. the invention be usedconjointly, since they may be employed advantageously in variouscombinations and sub-combinations.

What I claim is 1. In an excavating machine, the combination of apivoted boom; a vertically-digging bucket carried thereby; a line forhoisting the boom; and an articulated pressuretransmitting column memberconnecting the boom and bucket and depending from the end of the boomwhen the bucket is in digging position; the column member beingsufficiently flexible because of the articulations to be movable into aposition wherein it is generally parallel to the longitudinal axis ofthe boom; and power-actuated means to move the column memberlongitudinally.

2. In an excavating machine, the combination 01" a pivoted boom; anopposed action bucket carried thereby; a line for hoisting the boom; aline for hois ing the bucket; and a longitudinally movable,pressure-transmitting column extending vertically downwardly from theboom to the bucket and connected at its lower end to the bucket, saidcolumn being articulated at numerous points intermediate of its pointsof attachment to tl c boo-m and bucket so as to assume the flexibilityof a chain, when bent in one direction; said column having means toprevent bending thereof in the opposite direction.

3. In an excavating machine, the combination of a pivoted boom; aclamshell bucket; a power-actuated line for swinging the boom invertical planes; a power-actuated line for closing and hoisting thebucket; a linked member depending from the boom and connecting the boomand bucket, the links of said linked member contacting with each other,when the linked member is subjected to compression, so as to permit thetransmission of heavy thrusts longitudinally of the linked member, whensubstantially vertical;

said linked member being longitudinally movable by the bucket-hoistingline.

4. In an excavating machine, the combination of a pivoted boom; aclamshell bucket carried thereby; a line for hoisting the boom; windingmeans for closing and hoisting the bucket a linked member connecting theboom 1 and bucket; and a sprocket carried by the boom and supporting andguiding said linked member; the links of said member being soconstructed and arranged as to allow the linked member to turn aboutsaid sprocket but preventing more than slight relative disalignment ofthe links in the direction opposite to the one in which the links turnwhen passing over said sprocket.

5. In an excavating machine, the combination of a pivoted boom; aclamshell bucket carried thereby; a boom-hoisting line; a sheave uponthe boom about which said line passes; winding means for closing andhoisting the bucket; a column-chain connecting the boom and bucket; aholding-sprocket carried by the boom and engaging said column chain; andmeans operatively connecting said sheave and said sprocket wherebyrotation of said sheave in opposite directions may be employed to holdand release said sprocket.

6. In an excavating machine, the combination of a pivoted boom; aclamshell bucket carried thereby; a V boom hoisting line; a sheave uponthe boom about which said line passes; winding means for closing andhoisting the bucket; a column-chain connecting the boom and bucket; aholding-sprocket carried by the boom and engaging said columnchain; andcontrol means connecting said sheave and said sprocket, said controlmeans brake band, a brake lever, a link connecting the brake lever withthe arm, and a brake drum; said brake drum being operatively integralwith said sprocket.

7. In excavating machine, the combination of a pivoted boom; a ciamshellbucket carried thereby; boom hoisting line; a sheave upon the boom aboutwhich said line passes; winding means for closing and hoisting thebucket; a column-chain connecting the boom and bucket; holding-sprocketcarried by the boom and engaging said columnchain; and control meansconnecting said sheave and said sprocket, said control means comprisingan arm actuated by said sheave, a brake band, a brake lever, a linkconnecting the brake lever with the arm, and a brake drum; said brakedrum being operatively integral with said sprocket; and the link beingnon-resilient under tension but yielding to a limited extent tocompression, permitting the arm and link to have a toggle action at thebrake-setting end of travel of the arm,

serving to hold the arm and lever against accidental releasing movement.

8. In an excavating machine, the combination of a pivoted boom; aclamshell bucket carried thereby; a boom hoisting line; a sheave uponthe boom about which said line passes; winding means for closing andhoisting the bucket; a column-chain connecting the boom and bucket; aholdingsprocket carried by the boom and engaging said columnchain; andcontrol means connecting said sheave and said sprocket, said controlmeans comprising an arm actuated by said sheave, a brake band, a brakelever, a link connecting the brake lever with the arm, and a brake drum;said brake drum being operatively integral with said sprocket; and stopsfor limiting movement of said sheave-actuated arm so that the'arm andthe link may form a tog gle to hold the brake lever in brake-settingposition.

9. In an excavating machine, the combination of a pivoted boom; aclamshell bucket carried thereby; a boom hoisting line; a sheave uponthe boom about which said line passes; winding means for closing andhoisting the bucket; a column-chain connecting the boom and bucket; aholding-sprocket carried by the boom and engaging said columnchain; andcontrol means connecting said sheave and said sprocket, said controlmeans comprising an arm actuated by said sheave, a brake band,a brakelever, a link connecting the brake lever with the arm, and a brake drum;said brake drum being operativ-ely integral with said sprocket; stopsfor limiting movement of said sheave-actuated arm so that the arm an dthe link may form atoggle to hold the brake lever in brake-settingposition; and the link being non-resilient under tension but yielding toa limited extent to compression,

serving to hold the arm and lever against accidental releasing movement.

'10. In an excavating machine, the combination of a pivoted boom; a.clamshell bucket carried thereby; a boom hoisting line; a

sheave u on the boom about which said line passes; winding means forclosing and hoisting the bucket; a column-chain connecting the boom andbucket; a holding-sprocket carried by the boom and engaging said 001-umn-chain; and control means connecting said sheave and said sprocket,said control means comprising an arm having a frictional connection withthe sheave, a pair of stops for limiting movement of the arm so that thearm moves through an arc while frictionally clutched to thesheave, andthen encounters 1 one of the stops and ceases swinging, the frictionalconnection yielding to permit free continned I'OtEItIOII' of the sheave;said'control 1 means also comprising a brake connected to the sprocketto hold the sprocket a ainst ro- L .l. O

tation and mechanism connecting'the brake and the arm, said mechanismlocking the brake agalnst accidental releasing, when the arm abuts oneof the steps, but releasing the brakewhen the arm is near the otherstop.

11. An excavating machine comprising, in

combination, a pivoted boom; a member flexible in one direction; asprocketat the outer end of the boom over which the flexible member maymove; and storage means fast to the boom for receiving and holdingsubstantial.- ly the entire flexible member so as to be supported by theboom."

12. An excavating machine comprising, in combination, boom; a-fiexible'member which is substantially non-deformable by longitudinalcompression; and a rack carried by the boom and havin a plurality oftiers connected together to provide a continuous tracker guide torstoring substantially the entire flexible member on the boom.

13. An excavatin'gmachine comprising, in

combination, a pivoted boom; a clamshell bucket; means for raising andlowering the boom; and alinked member carried by the boom and attachedto the bucket, said linked member being substantially non-deformable bylongitudinal compression, so as to be capable of transmittlng boomWeight to the bucket durin QXCttVittlOIl' means carrled b the boom forholding the linked member against longitudinal movement; and a rackattached to the boom and extending along the underside of the boom, saidrack having a plurality of tiers connected together to providea'continuous track or guide, so that the linked member moves to the nexttier when the first tier holds its portion of the linked member, therack thereby, providing storage for substantially the entire linkedmember,

or as much thereof as is not'in use.

let. An excavating machine comprising, 1n

thereof and to elevate the bucket with its jaws held closed; a pivotedboom; a second line for elevating and lowering the boom; a linked memberconnected to the bucket and carried by the boom and constructed andarranged to transmit compression forces longitudinally; and means forcausing said linked member to automatically assume a slightly bowedshape when a compression force is imposed upon it.

15. An excavating machine comprising in combination, a bucket havingjaws; a line connected to the bucket to close the jaws thereof and toelevate the bucket with its jaws held closed; a. pivoted boom; a secondline for elevating and lowering the boom; a linked member connected tothe bucket and carried by the boom and constructed and arranged totransmit compression forces longitudinally; and a weighted arm at thelower end of said linked member, but above the bucket, bearing againstthe linked member to make it assume a slightly bowed shape when acompression force is imposed upon it.

16. An excavating machine comprising, in combination, a pivoted boom; aclamshell bucket; means for raising and lowering the boom; a linkedmember depending from the boom and attached to the bucket, said linkedmember being substantially non-deformable by longitudinal compression,so as to be capable of transmitting boom weight to the bucket duringexcavation; and means carried by the boom to provide a continuous trackfor storing substantially the entire linked member on the boom.

17. An excavating machine comprising, in combination, a bucket; a boom;means connecting the bucket with the boom comprising a linked memberspending from and movable relative to the boom; said linked membertransmitting compression forces when vertical; means carried by the boomfor temporarily holding the linked member from moving relative to theboom; an operatorcontrolled mechanism for controlling said holdingmeans; and means on the boom for storing the linked member.

18. An excavating machine comprising, in combination, a bucket; apivoted boom; a power driven line for raising and lowering the boom; alinked member carried by and movable relative to the boom and connectedto the bucket; means carried by the boom for temporarily holding thelinked member from moving relative to the boom; and mechanism actuatedby said boom line for controlling said holding means.

19. An excavating machine comprising, in combination, a pivoted, rigidboom; operating mechanism therefor; a linked member carried upon theboom and transmitting compression forces longitudinally withoutcollapsing; means on the boom for storing the linked member; a buckethaving jaws carried by said linked member; and a power-actuated line forclosing the j aws of the bucket; said line being so connected that itlifts'the bucket.

and moves the linked member longitudinally back upon the storing means,after the bucket jaws are closed.

20. An excavating machine comprising, in

combination, a bucket having jaws; a power line connected to the bucketto close the jaws thereof and to elevate the bucket with its jaws heldclosed; a pivoted boom; a second power line for elevating and loweringthe boom; a linked member connected to the bucket and carried by theboom and con structed and arranged to transmit compression forceslongitudinally; and means on the boom for storing said linked memberwhen the bucket is elevated to jacent the boom.

21. An excavating machine comprising, in combination, a bucket havingjaws; a line connected to the bucket to close the jaws thereof and toelevate the bucket with its.

a point adjaws held closed; a pivoted boom; a second jaws held closed; apivoted boom; a second line for elevating and lowering the boom; alinked member connected to the bucket and constructed and arranged totransmit compression forces longitudinally; a sprocket on the outer endof the boom for engagement with said linked member; a brake forgoverning rotation of the sprocket; brake controlling mechanism operatedby the boom elevating line; and means on the boom for storing saidlinked member when the bucket is elevated to a point adjacent the boom.

23. An excavating machine comprising, in combination, a clamshellbucket; a pivoted boom; a boom-supported member for holding the bucket;a power driven drum on the boom; a pair of drums on the shaft of thepower drum; a line wound up by each of said drums; a pair of sheaves forsaid lines at the outer end of the boom; a pairof sheaves for said lineson the bucket; the lines being rigged to close the bucket and elevateit; and means for guiding the lines.

24. A column chain for transmitting compression forces to clamshells andthe like comprising, in combination, a pair of parallel sprocketchains;yokes operativelyintegral with the pairs of oppose l inner linksof the chains and extending inplanes substantially at right anglesto'the longitudinal axes of the chains, but on one side of .the chains; anda plurality of spacer blocks integral with the several yokes; adjacentones of said spacer blocks touching each other to prevent anysubstantial deflection "of the column chain in one direction.

'25. A column chain for transi'nitting'compression forces to clamshellsand the like comprising, in combination, a pair of parallel sprocketchains; yokes integral 'witlrthe pairs of opposed inner links of thechains and extending in planes substantially at right angles to thelongitudinal axes of the chains, but on one side of the two chains; anda plurality of spacer blocks integral with the several yokes; each yokeandspacer block providing a T-shaped extension of each opposed pair oflinks, the ends of the heads of the T-shaped extensions beingsubstantially abutted when the column chain hangs pendently, so thatbending of the column chain in one direction is permitted to a veryslight degree and is positively limited. Y 26; A column chain forexcavating machines and the like comprising, in combination, a linkedstructure including a multiplicity of links which may turn relative toeach other in one direction; means on the links preventing anysubstantial turning ofthe links but permitting a very slightdisalinement in the opposite direction theaforesaid means, and thedisalined positions of the links relative to each other, preventingcollapsing of the chain under compression forces imposed longitudinallyof the chain.

27, A column chain for excavating machines and the like comprising, incombination, a linked structure including a multiplicity of links whichmay turn relative to each other in one direction; means on each linkadapted to abutlike means onthe two adj acent links to prevent anysubstantial turning of the links in the opposite direction; saidabutting means being very slightly spaced apart when the chain isstraight, so that when compression forces are imposed on the chainlongitudinally, the small spaces between the said abutting means aretaken up, and the chain assumes a slightly arcuate shape. v

28. A column chain for excavating machines and the like comprising, incombination, a multiplicity of pin-connected links which may turn freelyin one direction; stop means on certain of the links for permitting a.only very limited turning of the links in the opposite direction in thesame plane; and means to cause the chain to assume a slightly bowedshape, the chain bending until said stop means prevent further movement.

29. A columnchain for excavating maadjacent links to preventenysubstantial chines and the like comprising, in combination," amultiplicity of 'pivota'llyconnected links which may freely turn in onedirection stop means on, Certain of the links for'permittingonly verylimited turning of the links in the opposite direction infthe sameplane; and 'a' weighted arm on the lower end; ofthe chain and tending toturnthe chain in the direction which movement is limited by said stopmeans, so that said chain becomes slightly bowed assocn as pa'rt'ofitsw'eig 'h t" is supported on the floor of the excavation.

30. A column chain for excavating ma chines and the like comprising, incombination, a linked structure including a multiplicity of links whichmay turn relative to eachother in one direction; means on each linkadapted to abut like means on thetwoturning of the links in thevopposite direc tion; said abutting means being very slightly spacedapart'when the chain is straight; and

a counterweighted arm extending transversely of the chainand secured atan intermediate point to the lowest links of'the chain and bearingagainst the abutting means of the next higher link, so that whencompression stresses are imposed on the chain longitudinally, the smallspaces between the said abutting means are closed, and the chain assumesa slightly arcuate shape.

31. A column chain for excavating machines and the like comprising, incombination, a multiplicity of pivotally connected links which mayturnin one direction in the 100 plane of the chain; said links'carrying a,load, under tension; and means on certain of the links'for supporting acompression load; said means preventing the turning of the links in theopposite direction and in the 0 aforesaid plane, butpermittinga slightdisalinement of the links so that the chain, when subjected toacompression load, assumes a slightly arcuate shape, being bowed in theaforesaid oppositedirection. v 32A column chain for excavating machinescomprising a pair of parallel sprocket chains; yokes connecting opposedlinks of said chains; and means secured to the yokes and spacedfromthe'link pivots in a direc- 1 t'ion lateral relative to thechain,-said'means projecting longitudinally of the chain so as nearlyto'abut each other, and contacting with each other to make acompression-sustaining column of the chain, when the chain 120'v issubjected to compression longitudinally. 33. A column chain forexcavating machines c'omprisinga pair of parallel sprocket chains;T-shaped spacer blocks rigidly secured to the OppOsed l-inksof saidchains 2 and extending all in the same direction laterally of thechain,with the beads of each'T extendinglongitudinally .of the'ch'ain andalmost in contact with adjacent spacer blocks, above and below, when thechain is. pendant, 3

so that the chain may buckle slightly when a longitudinal thrust isimposed on it from the upper end and then may transmitvery heavycompression stresses longitudinally.

' '34. An excavating machine comprising, in combination, a boom; acolumnchain having pivoted links; and means on the boom for storing saidcolumn chain; said chain-storing 1 means comprising a racksecured to andextending 'along'the boom on theunder side,said rack having two spacedlongitudinal bars on each side, the pivots of the chain passing throughthe space between the bars on each side and the links ofthe chain beingon both sides of said bars and preventing substantial lateral movementofthe chain on the rack; said chain being movable longitudinally of therack by a thrust orpull longitudinally of the chain.

35. An excavating machine comprising, in

' combination, a boom; a column chain; a

power-actuated boom-hoisting line; means carried on the boom for storingthe column a chain; and 'means carried on the boom for preventingmovement of the column chain relative to the boom said last-named meansbeing actuated by power derived from the boom hoisting line.

36. An excavating machine comprising, in combination, a boom; a columnchain supported by the boom; a power-actuated boomhoisting line; meansfor preventing movement of the column chain relative to the j boom; andmechanism actuated by the boomhoisting line for operating said means tohold and release the column chain.

, 3' 7. An excavating machine comprising, in combination, a boom; acolumn chain supported by the boom and movable from a posi-. 40

' ed means for swinging the boom in a vertical plane; a chain carriedby'the boom and constructed and arranged to withstand heavy compressionstresses imposed longitudinally; said chain being composed of amultiplicity of heavy links so that the chain adds greatly to the weightof the boom; a vertically digging bucket on the outer end of the chain;means for elevating and lowering the bucket yielding 001m whose weightuniformly a;

creases with its length thereby to impose an effectively heavier thruston the bucket as the column chain descends from the support afforded bythe boom;

39; An excavating machine comprising, in combination, a clamshellbucket, a single power a'ctuatedline to close and to elevate saidbucket; a pivoted boom; a power-aw tuated line to swing said boomvertically; means supported by and releasably secured to the boom totransmit part of the boom weight compressively to the clamshell bucket;and means controlled by the boom swinging line to release saidboom-supported means to permit movement thereof with the bucket. v I i40. An excavating machine comprising, in combination, a pivoted boom; aclamshell bucket; linked means transmitting compression from the boomtothe bucket; means on the boom for locking the linked means againsthorizontal movement; and two independently controlled, power-actuatedlines, one being connected and arranged for closing, elevating andlowering the clamshell bucket, the other being connected and arrangedfor elevating and lowering the boom and being engageable with saidlooking means for controlling lockingand releasing of saidcompression-transmitting linked means.

41. A clamshell excavator comprising, in combination, a pivoted boom; aclamshell bucket; means on the free end of theboom to impose part of theweight of the boom on the bucket; and two independently controlledpower-actuated lines, one being connected and arranged so as to controlclosing of the bucket, elevation thereof, opening of thebucket andlowering thereof, the other line being connected and arranged to elevateand lower the boom; and operator-controlled means to lock and releasethe means on the end of the boom. 7

In testimony that I claim the foregoing as my own, I have hereto affixedmy signa-- ture.

ROBERT REX DOWNIE.

and chain; and means on the boom for storing the chain; the parts beingso constructed and arranged that the boom carries the entire unused partof the chain,-thereby increasing its weight and making the total weighteffective to bearagainst the bucket 5 to aid in digging hard material";thechain,

as it moves ofi the boom, forming an un-

